The present invention relates to animal milking machines or installations in general, and more particularly to improvements in apparatus or units which are used for cleaning, rinsing, flushing and/or sterilizing the milk conveying paths in such machines.
German Offenlegungsschrift No. 1,692,327 discloses a cleaning unit wherein a housing contains a vessel for a cleaning agent, a heating device for cleaning agent and several conduits containing valves whose operation is regulated by a programming device. The cleaning agent is admitted into a vacuum line which, together with the associated milking and milk conveying instrumentalities, is rinsed and sterilized in response to circulation of cleaning agent therein. The admission of cleaning agent into the vessel is carried out by hand. This presents serious problems, especially if the cleaning agent is of the type tending to form crystals which deposit in the vessel and/or in the conduits to thus constrict or actually clog the passage or passages for circulation of the liquid. Deposition of crystals can take place in response to short-lasting dwell of cleaning agent in the vessel.
It is further known to install in the vacuum line a liquid reservoir (equalizing tank) which insures that the vacuum line can receive and retain varying quantities of liquid. The reservoir is installed close to the vessel for the cleaning agent and its position relative to the vessel must be selected and maintained with a high degree of accuracy. If the level of the reservoir is too high, the vessel receives excessive quantities of dilutant (water) for the cleaning agent and the dissolved or dispersed cleaning agent is likely to overflow the upper edge of the vessel. If the level of the reservoir is too low, the vessel receives insufficient quantities of water. Moreover, manual admission of cleaning agent is time-consuming, especially in large milking installations.